Recently I picked up this Fred & Friends "Cool Jewels" ice cube molds.
I was excited to make pretty, fun ice cubes for my nephews who were visiting. I initially tested it with cranberry juice (something they wouldn't drink) but had disastrous results. The sugary juice made the ice cubes sticky and they melted all weird and gross in the glass of 7-Up I put them in.
So instead, I tried some of my Wilton gel food coloring. I stirred just a toothpick full into a bit of water in my squeeze bottle.
I shook the squeeze bottle up carefully so the gel was mixed up nicely. It looked brown at the time but I knew it would turn into a nice burgundy when the ice froze and set.
I used the squeeze bottle to carefully fill the molds as full as I could. I then gently transferred them into my freezer, where I set them on top of a frozen pizza box so they'd be stable. I forgot to knock the mold a bit to get air bubbles out - oops.
Here are the jewel ice cubes about an hour later. (Sorry the picture isn't great!) They're not sticky, but they definitely melt fast and leave color behind. (My fingers definitely got stained!)
For best effect, I make several batches the day before I expect nieces or nephews to arrive. I store them in a big bowl in my extra freezer. Then I dish them up in front of the children so they can see the pretty jewels plopping into their glasses of water or Sprite or some sort of clear drink that will best show off the colors.